Switching device



June 30,1925.

E. B. CRAFT swncnmc DEVICE 2 w m wi w w a Filed Deb, 2

UNITED STATES PATENT OFFICE.

EDWARD B. CRAFT, OF HACKENSACK, NEW JERSEY, ASSIGNOR TO WESTERN ELECTRICCOMPANY, INCORPORATED, 013 NEW YORK, N. Y., A CORPORATION OF NEW YORK.

SWITCHING DEVICE.

Application filed December 24, 1921.

To all whom it may concern:

Be it known that I, EDWARD B. CRAFT, a citizen of the United States,residing at Hackensack, in the county of Bergen, State of New Jersey,have invented certain new and useful Improvements in Switching Devices,of which the following is a full, clear, concise, and exact description.

This invention relates to selective switching devices, and moreparticularly to devices of the character commonly employed in automatictelephone exchange systems for establishing circuit connections.

The object of the invention is to provide a selective switchingmechanism suitable for use in telephone and other systems which ischaracterized by the simplicity of its structural design and itsprinciple of operation, and also by the relative economy with which itis capable of being manufactured A feature of the invention relates tothe provision, in a switching mechanism where-- in a passive terminalelement consisting of a bare wire conductor is arranged to coact with aplurality of movable bare wire conductors, each movable wire having apoint of cooperation with the passive wire, of means for selecting anyone of said movable wires and moving the same into contact with thepassive wire.

A further feature of the invent-ion consists in providing a switchhaving a set of passive wires arranged in cooperative relation to eachof a plurality of sets of movable wires with a step-by-step selectivemechanism for selecting and moving any set of movable wires intophysical engagement with said set of passive wires.

Other and further features of the invention will become clearlyunderstood from the description given hereafter and from the appendedclaims.

In the drawing, which forms a part of the application, Fig. 1 is a topplan view illustrating one type of selective switching mechanism towhich the invention is applicable. In this figure a portion of the framestructure is broken away in order to reveal more clearly the dispositionof the interior elements.

Fig. 2 shows a side view of the switching structure.

Fig. 3 shows a perspective view illustrating the relative arrangement ofthe movable and stationary terminal elements, and also Serial No.524,564.

the method employed for securing these elements to the stationary partsof the switch.

Fig. 4: is a detailed view of one of the frame plates.

As previously observed, switching devices of the type disclosed in thisapplication are especially suitable for use in telephone exchangesystems where connections are desired between an incoming circuit andany one of a plurality of outgoing circuits. In order to simplify theconstruction of the cooperating contact making elements and also tosimplify the operation of these elements whereby a resultant structureis attained which is economical. to manufacture and reliable in service,it is proposed to utilize bare wire conductors for the movable contactsand to move these conductors physically into engagement with passive orstationary contacts, likewise consisting of bare wire conductors.Depending upon the purpose for which the switch is used, the set or setsof stationary contact elements may comprise as many individual elementsor conductors as necessary. These stationary conductors are of anysuitable form and are supported by insulating members in position to beengaged by the coacting movable conductors. As shown in the switchillustrating the present invention, the stationary conductors are wovenin and out among a series of supporting insulating strips arranged in acircular fashion about the selecting elements of the device. The severalconductors of each set have a separate point of cooperation with thecorresponding conductors of the passive set. As shown in Fig. 1, thesemovable conductors extend radially toward the center of the structurewhere they have a crossing point with the several correspondingstationary conductors. A suitable selecting element. which may beoperated in a step-by-step fashion as shown in the present disclosure,or which might be operated in any kind of motion, serves to select anyone of a set of movable conductors and thereafter to cause this set ofconductors to make engagement with the stationary conductors.

Manifestly a switching device of this general character may be devisedfor any one of a wide variety of purposes in telephone and othersystems. It may serve as a line switch which 1s operated automaticallyextending the line over an idle outgoing trunk. It may serve in thecapacity of a directive switch, in which case the movable select-ingdevice is advanced in a directive movement under the control of impulsesfor selecting a certain one of the movable contact elements to extendthe connection over the desired path. It may also be utilized as aregister for recording the value of digits.

Referring particularly to the drawing, a description will now be givenof the construction of the switching device. The frame consists amongother elements of the two supporting plates 1 and 2 made from thinmaterial and skeletonized as illustrated in Fig. 1 to permit ofinspection and acces sibility. The plates 1 and 2 are formed with twoconcentric semi-circular portions, as best seen in Figs. 1 and a. Theinner portion of plate 1, for example, according to Fig. 4, has a seriesof equally spaced notches 14 around the circumference thereof. The solidmaterial between the notches 11 constitutes a corresponding series ofteeth 15 which are somewhat wider than the notches themselves. Thenotches 11 and teeth 15 of plate 1 lie in alignment with thecorresponding notches and teeth in the lower frame plate 2 at the bottomof the structure. The purpose of the notches 1-1 is to receive andretain the insulating strips 21, 22, etc. upon which the stationary barewire conductors are woven.

Considering first the construction of the stationary terminal portion ofthe switch, it will be seen in Figs. 1, 2 and 3 that a series ofvertically arranged strips 21, 22, 23, 21, 25 and 26, etc., made ofinsulating material, are arranged in a circular manner and serve tosupport the stationary conductors. The stationary conductors 72, T8, 71,75, 7G and 77 are each secured to the insulating strip 21, and eachconductor is then woven in and out alternately among the succeedinginsulating strips 22, 23, 24, 25, 26, etc. and is again secured at theother end to the last of these vertical strips. The fabric, thus formedof the conductors and insulating strips, is assembled in the switchstructure so that the upper and lower ends of the several insulatingstrips 21, 22, 23, etc. enter the corresponding notches 14 formed in theframe plates 1 and 2.

A series of slidable operating bars 16, 17, 18, 19, 20, etc. the purposeof which will be described hereinafter, are arranged as shown in Figs. 1and 4 in co-operation with the several teeth 15 on the frame plate 2.lVith the insulating strips 22, 23, 2 1, etc. in their respectivenotches 1% and with the selectable operating bars in position, the upperand lower guide bands 11 and 81 are adjusted to hold the insulatingstrips and slidable bars notched around their inner peripheries incorrespondence with the notching of the frame plates 1 and 2. The upperguide plate 11, for example, viewed in Fig. l, is retained in place bymeans of screws 12 and 13, thus securing the elements mentioned, wherebythe fabric forming the stationary contact port-ion of the switch isretained rigidly in place, while the slidable bars 16, 17, 18, etc. arepermitted sutiicient freedom to move upwardly and downwardly. Theslidable bars are in their normal position at the uppermost extent oftheir movement, seen in Fig. 2. In order to hold these bars in theirupward position, springs T8 are provided, the resilient ends of whichpass through the lower ends of the slidable bars.

In the switch shown, the passive terminal set consists of six terminalwires 72, 73, T l, 75, T6 and TT. It is obvious, however, that. a lessnumber or a greater number of passive terminal wires may be employed,these being dependent wholly upon the nature of the system in which theswitch is used. To increase the capacity of the switch in this respectit would only be necessary to add in a vertical direction otherconductors to the woven fabric.

The movable. terminal elements which coact with the passive terminalconductors are also comprised of plain bare wires arranged, as best seenin Figs. 1 and 3, in sets extending radially toward the center of thestructure. There are shown to be ten different sets of movable terminalelements corresponding to the digits of the decimal system. although ofcourse the number of sets of movable terminal elements may be varied tosuit the requirements. Each set of mo 'able terminal elements consistsof a plurality of bare wire conductors corresponding in number to thenumber of passive wires with which they cooperate. With particularreference to Fig. 3, the first set of movable elements is seen toconsist of the wires 62, (3 Get, (35, etc. These bare wires aresupported by an insulating block 3, through which their rigid ends passto the exterior of the structure and are there overturned to provide ameans for making soldered connections. Each of the remaining nine setsof movable wires is likewise secured to a corresponding insulating blocksuch as the blocks 4:, 5, (3, 7, etc. The last set of movable conductorsis visible in Fig. 2 and comprises the conductors 29, 30, 31, 32, 33 andThe springs for holding the bars 16, 17, 18, etc. in place, one of whichis shown at 78, are carried by the respective insulating blocks 3, 4-,5, etc.

The insulating blocks 3, l, 5, (i, 7, etc. when assembled in thestructure are received by a series of notches 79 arranged around theouter circumference of the frame plates 1 and 2. They are retained intheir assembled poillustrated in Fig. 1. The ends of the wire strap 8are secured to the frame plate by means of screws 9 and 10, thus bindingthe insulating blocks and holding them firmly in position.

The free ends of the movable terminal wires extend radially toward thecenter of the structure and pass through apertures in the correspondingslidable insulating bars 16, 17, 18, 19, 20, etc. These apertures, asbest seen in Fig. 3, are disposed at an acute angle, to the vertical,the purpose of which will be explained later on. After passing throughthe diagonal apertures in the slidable bar, the several conductors of amovable set extend in intersecting relation with the correspondingpassive wire terminals 72, 73, 74, 75, 76 and 77. Normally, when aslidable bar is in its uppermost position under the influence of aspring 78, the several movable conductors 62, 63, 64, 65, etc. rest inthe bottom of the-diagonal slots and are held. at an appreciabledistance from the corresponding passive elements.

Besides the movable terminal wires, such as in wires 62, 63, 64, 65,etc. of the first set, each set is provided with an additional Wireterminal 61, likewise secured to the terminal block and also passingthrough a slot in the slidable bar 16. This wire is arranged at the topof the set, and as seen extends inwardly to the center of the structureto a greater distance than connecting wires of the set. Its functionwill be explained hereinafter.

A rotatable shaft 42 is located at the center of the switch. and isjournaled for rotation in any suitable fashion in the frame plates 1 and2. The uppermost end of the shaft 42 carries a member 43 having twodiametrically extending arms, the outer ends of which traverse the arcof a circle coincident with the circle around which the slidable bars16, 17, 18 and 19 are arranged. As seen in Fig. 1, selecting arm 43 isalways in a position to advance one of its projections over the top ofone of the slidable bars. As one arm moves away from the last slidablebar, the dimetrically opposite arm is moved over the first slidable barat the other extremity of the semi-circumference.

A ratchet Wheel 47 is mounted on the shaft 42 at some convenient pointbetween the frame plates 1 and 2. The ratchet wheel 47 is acted upon bya stepping pawl 57 for rotating the shaft 42 in a step-by-step manner toadvance the selecting arm 43 from one slidable bar to another. Thestepping pawl 57 is attached to the armature 52 of an electromagnet 51,which is mounted in any dosirable manner upon the frame of the switch.Normally the armature 52 is held in its position, shown in Fig. 1, bythe action of a retractile spring 53. WVith the armature 52 in withdrawnfrom engagemeiit with the teeth of the ratchet wheel 47 and restsagainst a stop pin 80. Moreover, a pair of electrical contacts 54 and 55are held in engagement with each other by an insulating stud 56 carriedon the armature 52, while the magnet is deenergize'd and its armature isin normal position.

The lower portion of the shaft 42 serves as the plunger element for asolenoid 48. The winding of the solenoid 48 is mounted on the frameplate 2 surrounding the plunger shaft 42. The shaft 42 is thereforeslidable in a longitudinal direction as well as being arranged forrotation. Normally, said shaft is held in its uppermost position bymeans of a spring 49. When in its normal condition, the selecting arm 43is disposed with its projecting arms slightly clearing the tops of theslidable bars 16, 17, 18, etc.

A conducting ring 44 having two oppositely extending brushes 45 and 46is securely fastened to the shaft 42 bet-ween the ratchet 47 and theupper frame plate 1. The brushes 45 and 46 are turned upwardly, as seenin Fig. 3, and are adapted to cooperate with the topmost wire of eachset of movable wires. In Fig. 3, the brush 46 is seen to be inengagement with the wire conductor 66. In order to feed current to therotating rin 44, there is provided a feed brush 41, which extendsinwardly, as seen in Fig. 2, and bears on the continuous surface of thering 44, thereby making contact therewith constantly.

A brief description will next be taken up giving the operation of theswitch. Assume that the switching device is in its normal position whenthe selecting arm 43 is disposed as illustrated in Fig. 1. suitablecircuit arrangement. a number of directive impulses may be sent toenergize electromagnet 51 a corresponding number of times. Uponenergizing, the magnet 51 attracts its armature, forcing the pawl 57against a tooth of the ratchet wheel 47 and rotating the shaft 42together with the selecting arm 43 and the feed ring 44 forward onestep, positioning said arm directly above the first slidable bar 16.Upon the deengization of the stepping magnet 51, the pawl 57 iswithdrawn, and for each following energization, the shaft 42 is steppedforward until the selecting arm 43 is positioned above the slidable barcorresponding to the number of impulses sent to the switch. During therotation of the shaft 42, the teeth of the ratchet wheel pass over thefree end of a retaining spring 50, which serves to accurately positionthe shaft at the end of each impulse, and determines that the forwardmovement of said shaft takes place in increments corresponding to theteeth on the ratchet Wheel.

After the set of movable terminal wires By any cution is created 1n thecircults or the system for causing the energization of the solenoid 18.The solenoid 4S draws down the shaft 42, moving the selecting armagainst the end of the slidable bar corresponding to the selected set ofmovable wires. The continued downward motion of the shaft 42 also movesthe slidable bar downwardly against the resistance of the spring 78. Atthe first downward movement of the slidable bar, the movable wirespassing through the diagonal slots of this bar are carried into physicalcontact with the respective stationary wires. The continued movement ofthe bar, through the agency of. the diagonal slots. produces a cammingaction on the movable wires, causing them to be dis placed laterallywhile in physical'contact with the passive wires. The purpose of thisaction is to produce a rubbing etlect between the movable and stationarywires in order to maintain good electrical contact surfaces.

lVhen the connection is no longer re quired, the solenoid 48 isdeenergized and the shaft 4-2 is permitted to restore to its normalupward position, releasing the slidable bar and thereby permitting themovable contacts of the corresponding set to dis engage the stationarywires. The switch may be restored to its normal position by energizingthe stepping magnet 51 the proper number of times.

It may also be desirable to use of this character in the capacity ofmatic hunting switch. In this case the circuit for the electromagnet 51extends through the contacts 5% and which are normally closed when thearmature is in its retracted position. By closing the energizingcircuit, the magnet 51 attracts its armature, advances the shaft 42forward one step. opens the contacts and 55, thereby severing thestepping circuit of the magnet. which in turn becomes deenergized andretracts its armature. The retraction of the armature closes thecontacts 5% and and again the switch takes another step forward. At eachstep one of the brushes 45 and 46 makes engagement with the upper wires(31. 66, etc. which may be adapted in any well known manner to form atest. It the set of movable contactsat a given position isnon-selectable, then the brush 45 or t6 will a device an autodiscover anelectrical condition upon the test wires 61, 66. which determines thatthe stepping circuit of the switch shall be maintained closed. IVhen aselectable set of movable contacts is reached, a diii erent electricalcondition is "found by the brush L5 or 46, and in any obvious manner thestepping circuit of the magnet 51 is open-ed, causing the switch to cometo rest.

hype UI ll S VlLCll.l1lg SLII'UULLUIU, lb '111 UU understood that thesame is applicable to a wide variety of forms of switch mechanism, andshould not be limited to immaterial details of construction. Forexample, the invention is also applicable to a switching structure inwhich the selecting element moves in a straight line, or in which two ormore separate and distinct movements are performed by the selectingdevice.

lVhat is claimed is:

1. In a switching mechanism, a bare wire conductor serving as a passiveterminal element, a. plurality of movable terminal ele ments, eachhaving a point of cooperation with said passive wire. and a singleselectively operable device for selecting one of said movable terminalelements and for moving the selected element into contact with saidpassive wire.

2. In a switching mechanism, a bare wire conductor serving as a passiveterminal element, a plurality of movable terminal elements, each havinga point of cooperation with said passive wire, av single selectivelyoperable device for selecting one of said movable terminal elements, andelectromagnet-ic means for moving the selected element into contact withsaid passive wire.

3. In a switching mechanism, a bare wire conductor serving as a passiveterminal element. a plurality of movable terminal ele ments. each havinga point of cooperation with said passive wire, a selecting device, meanstor selectively moving said device to the point of cooperationcorresponding to any one of the movable elements. and means for movingthe selected element into contact with said passive wire.

l. In a switching mechanism, a bare wire conductor serving as a passiveterminal element, a plurality of movable terminal elements, each havingapoint of cooperation with said passive wires. and a step-by-stepoperated device for selecting one of said movable terminal elements andfor moving the selected element into contact with said passive wire.

5. In a switching mechanism. a bare wire conductor serving as a passiveterminal element, a plurality of movable. terminal elements, each havinga point of cooperation with said passive wire, a rotatable selectingdevice for selecting one of said movable terminal elements, anelectromagnet for operating said selecting device. and means for movingthe selected element into contact with said passive wire.

6. In a switching mechanism. a bare wire conductor serving as a passiveterminal element, a plurality of movable terminal, elements, eacharranged to cooperate with said passive wire, a selecting device forselecting one of said movable terminal elements, an electromagnet foroperating said selecting device, and an electromagnetfor moving theselected element into contact with said passive wire.

7. In a switching mechanism, a bare wire conductor serving as a passiveterminal element, a plurality of movable terminal elements, eacharranged to cooperate with said passive wire, a rotatable selectingmember, an electromagnet for rotating said member to select one of saidmovable elements, and a second electromagnet for moving said rotatablemember in a second direction to move the selected terminal element intocontact with said passive wire.

8. In a switching mechanism, a bare wire conductor serving as a passiveterminal element, a plurality of movable terminal elements arranged inintersecting relation with said passive wire, and a single selectivelyoperable device for selecting one of said movable elements and movingthe same into contact with said passive wire.

9. In a. switching mechanism, a bare wire conductor serving as a passiveterminal element, a plurality of movable terminal elements, each havinga point of cooperation with said passive wire, a plurality of slidablebars, one for each point of cooperation, a selectively operable devicefor selecting and operating any one of said bars to move thecorresponding movable terminal element .into contact with said passivewire.

10. In a switching mechanism, a bare wire conductor serving as a passiveterminal element, a plurality of movable bare wires serving as movableterminal elements and arranged to cooperate with said passive wire, anda single selectively operable device for selecting one of said movablewires and for moving the same into contact with said passive wire. 1

11. In a switching mechanism, a bare wire conductor serving as a passiveterminal ele ment, a plurality of movable bare wires serving as movableterminal elements and arranged in intersecting relation with saidpassive wire, and a single selectively operable device for selecting oneof said movable wires and for moving the same into contact with saidpassive wire.

12. Ina switching mechanism, a set of bare wire conductors serving aspassive terminal elements, a plurality of sets of movable bare wireconductors arranged in cooperative relation with said set of passivewires, and a. selectively operable device for selecting one of said setsof movable wires and for moving the same into contact with thecorresponding wires of said passive set.

13. In a circuit controller, a pluralty of passive contact elements, aplurality of movable" contact elements, a plurality of contact operatingdevices, an operating member common to said devices and selectivelyengageable therewith, and means for moving said operating member tocause said movable contact elements to move in more than one directionwith respect to said passive contact elements.

14. In a circuit controller, a plurality of passive contact elements, aplurality of movable contact elements, a plurality of contact operatingdevices arranged in the arc of a circle, an operating member common tosaid devices and selectively engageable therewith, and means for movingsaid operating memher to cause said movable contact elements to move inmore than one direction with respect to said passive contact elements.

15. A circuit controller comprising a series of movable contactoperating devices arranged in the arc of a circle, sets of movablecontacts carried thereby, other sets of passive contacts, an operatingmember common to said series of contact operating devices, and means,for moving said operating member to cause a rubbing action between saidmovable contacts and said passive contacts.

In witness whereof, I hereunto subscribe my name this 22nd day ofDecember A. D., 1921.

EDWARD B. CRAFT.

